A method is known in which surround-channel sounds are caused to reach a sound receiving point by having them reflected by wall surfaces utilizing a phenomenon that a sound that is output from a speaker array in which plural speaker units arranged regularly exhibits beam-like directivity. For example, Patent document 1 discloses a technique of causing left and right surround-channel sounds emitted from a speaker array installed right in front of a sound receiving point to reach the sound receiving point by having reflected by wall surfaces. With this technique, virtual speakers are formed in directions of wall surfaces that are located on the left and right of a sound receiving point.